10 Gigabit Ethernet (10GbE) is a set of Ethernet standards with a nominal data rate of 10.3125 Gbit/s. 10GbE over fiber, copper cabling and twisted pair are specified by the IEEE 802.3 standard. IEEE 802.3 is a collection of standards defining the physical layer, and the media access control (MAC) sublayer of the data link layer for wired Ethernet. IEEE 802.3ap, for example, provides a standard for Backplane Ethernet over printed circuit boards, with rates of 1.25 and 10.3125 Gbit/s.
The IEEE 802.3ap standard defines the physical medium dependent sublayer (PMD) control function. The PMD control function implements the 10GBASE-KR start-up protocol, which provides a joint adaptation mechanism through which the local receiver can tune the link-partner transmit equalizer to optimize performance over the backplane interconnect, and to inform the link partner when training is complete and it is ready to receive data. This mechanism is implemented through the continuous exchange of fixed-length training frames. These training frames are used by the two physical layer devices to exchange control and status information necessary to configure the adaptive equalization filters for both devices.
A number of joint equalization adaptation techniques have been proposed or suggested for use with the 10GBASE-KR standard. These existing techniques, however, are typically based on a primitive eye diagram visual examination or on an incomplete mathematical derivation, with inadequate assumptions. Consequently, the resulting implementations are not sufficient or complete. More often, these existing proposals are overly complicated, and may degrade the overall link performance.
A need therefore exists for improved methods and apparatus for joint adaptation of the transmitter transversal filter in Serializer-Deserializer (SerDes) devices.